1. Field of the Invention
The present invention relates to a method of fabricating a thin film transistor of a thin film transistor liquid crystal display (TFT-LCD) and a method of fabricating a liquid crystal display. More particularly, the present invention relates to a method of fabricating a thin film transistor of a thin film transistor liquid crystal display (TFT-LCD) and a method of fabricating the liquid crystal display by damascene process.
2. Description of the Related Art
With the rapid progress in the fabrication of semiconductor devices and man-machine interfacing devices, multimedia technologies are deployed everywhere in our society. In the past, cathode ray tubes (CRT) were one of the most important display devices in the market due to their high display quality and moderate pricing. However, in an environment where a large number of desktop operated terminals/display devices are used, energy consumption is also a very important consideration. Because a CRT wastes a lot of power and has a poor spatial utilization, other types of display devices having higher display quality, greater spatial utilization, lower power consumption and capable of radiation-free operation such as the thin film transistor liquid crystal display (TFT-LCD) gradually take over. In fact, TFT-LCD has become one of the mainstream display devices in the market.
The conventional method of fabricating a thin film transistor includes forming a gate on a substrate and then forming an insulating layer and a semiconductor layer sequentially over the substrate to cover the gate. Thereafter, a source and a drain are formed on the semiconductor layer to form a thin film transistor.
In the conventional method of fabricating the thin film transistor, a photolithographic and etching process is used to pattern metallic layers for producing the gate, the source and the drain. Thus, the metallic layers must have a property that matches with the liquid etchant or gaseous etchant used in the etching operation. Therefore, a metal having an ideal etching property such as aluminum to form the metallic layer is selected in the prior art. However, when this type of material is used, the materials that can be used to form the electrodes of the thin film transistor are limited. In particular, because aluminum has a higher resistance relative to other metals, the increase in electrical resistance as the device miniaturization will directly affect the performance of the thin film transistors.